The integrated biopsychosocial model of chronic low back pain (cLBP) acknowledges that interactions of biological, psychological and social factors determine the course of LBP. The goal of this research core is to contribute the bio-behavioral perspective. In close cooperation with the other cores of UCSF REACH, it will add the neuroscience and psychological expertise and state-of-the-art technology to be integrated with biomechanic and structural parameters. This CORE will leverage existing resources (SFVAHCS MRI), existing clinical cohorts (Spine Center; SFVAHCS), and existing datasets to conduct bio-behavioral research leading to further characterization of LBP mechanisms and improved phenotyping of patients with cLBP. We will accomplish these goals with the following Specific Aims: Aim 1: To provide, maintain, and support state-of-the-art self-report measures, quantitative sensory testing (QST) and brain imaging methods for evaluating and classifying individual processing of cLBP: A. Behavioral Self-Report Measures / Patient-Reported Outcomes using a comprehensive battery of a) NIH- recommended, b) validated supplemental and c) emergent psychological self-report outcome measures. 1) Quantitative Sensory Testing to assess perception, pain and tolerance thresholds, and various indices assessing endogenous pain modulatory capacity using validated psychophysical tests. 2) Functional MRI with application of an experimental pain task to separately evaluate components of the pain experience and determine which neural networks are mostly affected by variations of cLBP phenotypes. 3) Structural MRI and Diffusion MRI to assess cortical/subcortical structural plasticity and microstructure within various cLBP phenotypes. Aim 2: To provide infrastructure for validation and clinical utility determination for the emerging biobehavioral data elements in individuals with cLBP We will facilitate evaluation of the clinical utility in a separate sample of individuals with cLBP undergoing an intensive pain rehabilitation program. Data will be fed continuously into the Informatics Core and analyzed in close cooperation with all Cores of the Mechanistic Center and with other Centers across the BACPAC Consortium. Aim 3: To develop and provide evidence-based novel interventions for cLBP. To strengthen the Bio-Behavioral Core's capabilities for studying innovative behavioral treatment approaches, we will develop and validate innovative interventions based on mindfulness-based theories. Aim 4: To provide forums for stimulating collaboration, learning, and improving upon our current approaches where we will present new research and technology innovation to the REACH and BACPAC communities.